Method and apparatus for forming the rims of cylindrical shells



April 29, 1941- D. BOHM 2,239,696 METHOD AND APPARATUS FOR FORMING THERIMS 0F CYLINDRICAL SHELLS Filed May 29, 1936 5 Sheets-Sheet l INVENTOR.

ATTORNEYS A ril 29, 1941. D. BOHM 2,239,696

METHOD AND APPARATUS FOR FORMING THE RIMS 0F CYLINDRICAL SHELLS FiledMay 29, 1936 5 SheetsSheet 2 I N VENTOR.

,DanL'eZ 507m? 7 v v a l I l 5 ."II'IIIIIIIIIII'IIIIIIA 6 l t z 3 Z aATTORNEYS D. BOHM April 29, 1941.

METHOD AND APPARATUS FOR FORMING THE RIMS OF CYLINDRICAL SHELLS FiledMay 29, 1936 5 Sheets-Sheet 5 iilriiilllilliill vlllllilfllllll\INVENTOR. Pan/e/ 207m ATTORNEY.

April 29, 1941. D. BOHM 2,239,696

METHOD AND APPARATUS FOR FORMING THE RIMS OF CYLINDRICAL SHELLS FiledMay 29, 1936 5 Sheets-Sheet 5 INVENTOR. flannel Bohm ATTORNEYS PatentedApr. 29, 1941 METHOD AND APPARATUS FOR FORMIN THE RIMS OF CYLINDRICALSHELLS Daniel Bohm, Salem,

Ohio, assignor to Mullins Manufacturing Corporation, Salem, Ohio, a.corporation of New York Application May 29, 1936, Serial No. 82,617

21 Claims.

This invention relates to the method and apparatus for forming rims ofdrawn cylindrical shells and has to do particularly with the forming ofthe necked-in top or rim portion of washing machine tubs, buckets andthe like.

During recent years it has been the practice to form washing machinetubs and the like with a distinct necked-in formation as contrasted withprior art practice of merely forming a relatively small bead at the topperiphery of the cylindrical tub. The forming of this distinct necked-inportion, with or without the bead has been the source of much diflicultyand requiring extensive fabricating steps.

It is the object of the present invention to form a distinct "necked-inportion of relatively great depth adjacent the top portion of acylindrical tub or the like by a simple, cold Working operation whichembodies substantially holding one point of two spaced portions of awall of a rotating member in a fixed plane and drawing out theintermediate portion of the wall by a rotating forming die.

An important step in my method of fabrication has to do with the curlingover of the edge of the tub and the utilization of the curled overportion as a fixed or fulcrum point with relation to which a portion ofa cylindrical wall is drawn or necked-in; the direct result of this stepis that the curled over portion or bead is rotated and maintained in asubstantially fixed plane while the portion of the tub adjacent thecurled over portion is subjected to successive drawing operations.

Still another feature has to do with a combined necking-in and trimmingstep wherein simultaneously with the completion of the neckingin of thetub, another portion of the tub is trimmed off; this trimmed off portionbeing the fulcrum point with relation to which the metal was stretchedor drawn during the main forming step.

A still further feature has to do with the step of and means formaintaining the tub or other article in a straight sided cylindricalshape during the necking-in operations. Further features have to do withdetails of the progressive fabricating steps and fabricating means forcarrying out the steps as will be more clearly set forth in thespecification and claims.

In the drawings:

Fig. l is a view, partly in cross section and largely diagrammatic,illustrating the step of drawing a cylindrical unit such as a washingmachine tub.

Fig. 2 is a view similar to Fig. 1 but showing the second, or sizing,operation.

Fig. 3 is a view largely diagrammatic illustrating the trimming andcurling steps.

Fig. 4 is a view taken at right angles to Fig. 3 and showingdiagrammatically the means for successively trimming and curling theedge of the tub.

Fig. 5 illustrates the step of subjecting the tub to forming rolls of apeculiar shape, the bead of the tub being held in a fixed plane by agroove in one of the forming rolls.

Figs. 6 and '7 illustrate successive operations in getting the finaldepth required for the necked-in portion of the tub.

Fig. 8 illustrates the final step of forming and shearing.

Fig. 9 is a cross sectional view illustrating diagrammatically thecontour of a necked-in tub formed in accordance with the present inven-Fig. 10 is aview similar to Fig. 8 but illustrating a slightlyv modifiedfabricating step in that the side walls of the tub are progressivelymaintained straight and cylindrical during the necking-in and shearingsteps.

Fig. 11 is a sectional view taken on line IIH of Fig. 10 andillustrating in particular the clamping or latching means for holdingthe retaining ring in place.

Figs. 12 to 14 illustrate the three steps of necking-in and trimming atub, utilizing feeding rolls of slightly different construction thanshown in Fig. 10.

Fig. 15 illustrates the step of forming a relatively deep necked-inportion in one operation.

The successive figures of the drawings, particularly Figs. 1 to 8,disclose the important steps in carrying out my invention in connectionwith the formation of the rim portion of washing machine tubs, andsimilar cylindrical containers. In Fig. 1, I have illustrated, more orless diagrammatically, the step of initially drawing a rough tub formfrom a flat sheet, the cylindrical wall of the tub or shell beingindicated as at 2 and the rim flange as at 3, the usual forming memberscomprising a draw ring 4, a hold-down ring 5 and a punch 6.

In the second step as illustrated in Figure 2, a pad member I is shownas forming and defining the bottom contour of the tub or shell, a sizingring 8 and a flattening ring 9, providing a finished size and contourfor the upper portion of the tub.

Next the formed tub. which is indicated as at matically the tub beingheld in place between a tail stock clamp l and a mandrel ll. As bestshownin Fig. 4 a rocker arm l2 may be oscillatably mounted about a pivotI! carried by the lathe or other machine tool, such rocker arm carryinga trimming tool II and a curling tool l5. Although Figure 3 shows theupper edge of the tub being trimmed and curled simultaneously, this isfor illustration only, as in actual opera- .tion, the rocker arm l2 willfirst be moved to trimming position to trim thefiange 3 of the tub, asillustrated in Figure 4, after which trimming operation, the rocker armwill be moved about the pivot I3 to subject .the rotating trimming edgeto a curling action by the tool l5, whereby to curl the top edge of thetub as at to.

The initial step of actually forming the bead in the rim of the tub isillustrated in Figure 5 wherein a radially stationary forming roll isshown at l6 and a radially reciprocable forming roll at IT. Themechanism for carrying and actuating the tooling rollers I 6 and I1 isnot shown, but it will be understood that such rollers may be carriedand actuated by a machine such as shown in the patent to Horvath,1,850,958 of March 22, 1932. It will be understood that severaloperations may be necessary in order to get the final depth of beadrequired, with the result that the rim of the tub may be subjected tosuccessive sets of forming rolls in order to produce the final tub rimshape.

The rolls l6 and- I1 shown in Figure 5, are

s an example of the initial forming rolls that may be used, the radiallystationary roll l6 having an annular depressed forming surface I 8 andthe reciprocable roll l1 having a complemental raised forming surfacel9. An important feature of the initial forming rolls l6 and I1, as wellas the rolls used in forming the bead a, is the annular groove 2| formedat one end of the reciprocating roll II. This groove is of such size asto receive the rolled edge 3a of the tub, the purpose of this groove 2|being to retain tool the final forming roll shown in Figure 8 is thepositioning and formation of surfaces 22 and 23, formed as a part of therolls [8a and Ha, respeotively; as the movable roll nears the end of itstravel in finally shaping -the bead 20a the two surfaces 22 and 23cooperate to trim away the curl 3a and other excess material from therim of the tub.

It will be distinctly understood that in some cases the initial formingrolls may take the shape and perform the operation of the final rolls asshown in Figure 8, but in the practical carrying out of my methodwherein the shape desired for the bead approaches that disclosed therolled edge 3a in a fixed plane during the I complete formingoperations. It will be understood that, while I prefer to use the-outerroll I! as a reciprocating roll, regardless of which roll isreciprocated or whether they are both partially reciprocated, theessential point is that the bead 3a is retained in afixed plane so thatin Figure 9, I have found it best to use two or more sets .of rolls. Inalso carrying out the steps, I prefer to use a pressure shoe 24 forcontacting the bottom of the tub or other article and a supportingsurface 25 upon which the shell rim rides during rotation.

It will thus be seen that by forming a curled edge at the rim of the tuband-utilizing this curled edge as a hold-down for the revolvingperiphery of the tub, I am able to draw the head to substantially anyshape desired by a simple, cold rolling operation. No heating orannealing of the tub is necessary and the flow of metal during therolling operation is even and uniform. It will also be understood thatsome tubs or similar articles may require the top curl So as a part ofthe finished shape, in which case the curl would not be trimmed oil inthe final operation. In other cases it may be required to have a curlformed at the apex of the formed bead, in which case it may be necessaryto trim oil the hold-downbead and form an additional bead at the trimmedrim of the tub. Figure 9 illustrates the general contour of a tubfinished in accordance with the stepsillustrated in Figures 5 to 8, butit will be understood that the rim of the tub or other similar articlemay be given any one of many widely varying forms and still come withinthe method steps covered by the present invention.

In Figures 10 and 11, I have showna slightly modified arrangement havingforming rolls I 6b and I'll: wherein the actual forming portion |9b isheld in position by suitable spacers, the upper spacer of which is ofsuch small diameter as to permit the use of a retaining ring 26, thepurpose of which is to maintain a straight sided tub when the tub ware2a is drawn or formed in the rim of the tub the metal is drawn from apoint intermediate the edge and thebottom of the tub and does not pullaway from the edge; in other words, the important point'here is toprovide a hold-down-for the rotating edge of the tub during the drawing,bending, spinning and forming of the bead.

After the initial forming of the necked-in portion or head 20, the tubmay be subjected to a second and third set of forming rollers so as toproduce the rim shapes as shown at Figures 6 and 7, it being understoodthat the shapes shown are illustrative and may vary widely in accordancewith the final design and shape required. In Figure 8, .I have shown therim of the tub as being subjected to the 'flnal forming and shapingoperation and the efie'ctive forming surface 19a on the rollerv l'lacooperating with the effective forming surface l8a on the wall 2a duringthe "necking-in operations. It will be obvious that this retaining ringwill prevent bulging out of the side walls of the tub at the start ofthe necking-in operation. As best shown in Figure 11, the retaining ring26 is formed in two parts hinged together at 21, and adapted to be heldin closed position by means of a spring latch 28. The split ring isslipped over the tub as. shown in Figures 10 and 11, before the rollingoperations are performed and maintains the diameter of the tub, at apoint adjacent the part to be necked-in, during the rolling operations.

' necked-in portions in a single operation. Here rollers I 6a to producethe final desiredshape Mia I or the rim section. An important feature oithe retaining groove is dispensed. with and a hold-down or reinforcingeffect on the edge is obtained because the rolled over head 3a isrelatively stifl' andoffers resistance to any change in diameter of thetub. During the final shearing step, as shown in- Fig. 10, the bead Sowill "contact with the bottom of the member l 912; Fig. .10 showing "thetrimmed ofi' curled edge as falling after being cut off. Thus while thecurled edge may be spaced from the forming roll at the start. of theforming operation, it may be said to be maintained below the effectivesurfaces of the forming rolls and between planes defined by relativelynarrow limits during the entire forming operation and during the lastpart of the forming operation when the bead contacts with the bottom ofthe roll, it will be maintained in a positive fixed plane.

In Fig. 12 I have illustrated a further modification wherein innerforming roll I60 takes the general configuration of the roll 16 shown inFig. and outer forming roll I90 takes the general configuration of theforming roll l9b shown in Fig. 10. In this modification a trimmingmember 220 is carried as a part of the inner forming roll I60, the edgeof the trimming member cooperating with a groove 230 formed in the rollI90. Similar to the showing in Fig. 10, a retainer ring 26 is utilizedin this modification and the forming rolls I60 and He are so positionedrelative to the edge of the tub that the curled edge 3a is spaced ashort distance below the cutting plane formed by the member 220 and thegroove 230.

In Fig. 13 the rotating forming rolls are shown as being moved relativeto each other to initiate the necking-in of the top part of the tub. Asillustrated in this figure, it will be seen that the curled edge 3astill operates as a hold-down or reinforcing means to permit necking-inof the top part of the tub during the rotating and forming step. Whilesome of the metal flows from the curled edge during the necking-in step,as is best illustrated in Fig. 14 this curled edge still operates as asort of floating hold-down reinforcement until it contacts with thebottom surface of the forming roll l9c where the contact continues untiltrimming off of the open end of the tub. Thus while the distance betweenthe curled edge 3a and the bottom surface of the forming roll I9cchanges slightly as the neckedin portion is gradually formed in a singleoperation, nevertheless, as far as the actual effect is concerned, thiscurled edge or hold-down operates as though it were maintained exactlyin the same plane and even though some metal flows from the curled edge,it operates as a hold-down reinforcement until the final trimming step.

In the event of a relatively deep necked-in portion the trimming member220 may be removed, as best shown in Fig. 15, which permits forming ofthe relatively deep necked-in portion in a single operation. In thiscase it will be seen that even more metal is taken from the curled edge30. but that such edge still maintains its hold-down and reinforcingproperties, and, of course, will contact with the bottom surface of theroll I90 during the greater part of the final forming operation.

What I claim is:

1. The method of forming rims of washing machine tubs and similararticles which comprises curling over the edge of the tub, setting uprelative movement betweenthe tub and forming units, subjecting the rimportion of the tub to the forming units, whereby to give said rimportion a predetermined shape, maintaining said curled edge in asubstantially fixed plane during said forming action and shearing offsaid curled edge at the completion of said forming step and during therelative movement between the tub and the forming units.

2. The method of forming a bead in the surface of a substantiallycylindrical sheet metal member which comprises curling over one edge ofsaid cylindrical surface, subjecting only a localized portion of saidsurface adjacent said edge to a drawing action whereby to form arelatively deep annularbead, causing relative movement between thecylindrical member and the forming means, said curled over edge actingas a reinforcing means in controlling the flow of metal during theforming process.

3. The method of forming rims of washing machine tubs and similararticles which comprises giving the edge of the tub a predeterminedshape, subjecting the rim portion of the tub to relatively movablerotating forming rolls, said forming rolls cooperating with saidpreformed edge whereby to maintain said edge in a substantially fixedplane during the forming action of the rolls upon the rim, subjectingsaid rim portion to a plurality of sets of forming rolls and maintainingsaid preformed edge in the same plane during the successive formingactions on the rim and shearing off said preformed edge as a step in thefinal forming of the rim.

4. A mechanism of the character described, comprising rotating formingrolls, one being reciprocably movable relative to the other, one of saidforming rolls having a shouldered portion adapted to receive a preformededge formed as a part of the article being subjected to forming .actionby the rolls whereby said shouldered portion and preformed edgecooperate as a holddown to maintain said edge in a substantially fixedplane during the movement of one of the forming rolls towards the otherand complemental surfaces formed on said forming rolls and cooperatingupon the final forming action to shear off said edge.

5. A mechanism of the character described, comprising rotating formingrolls, one being reciprocably movable relative to the other, one 'ofsaid forming rolls having a shouldered portion adapted during at leastpart of said reciprocal movement to receive a preformed edge formed as apart of the article being subjected to forming action by the rollswhereby said shouldered portion and a portion of said other rollcooperate to maintain said edge beyond said cooperating portions duringthe movement of one of the forming rolls towards the other, said formingrolls being so shaped and spaced relative to each other that a retainerring may be positioned between the shafts of the respective formingrolls and clamped around the article being formed and complementalsurfaces formed on said forming rolls and cooperating upon the finalforming action to shear off said edge.

6. The method of forming a bead adjacent the periphery of asubstantially cylindrical sheet metal member which comprises curlingover one edge of said cylindrical surface, subjecting a portion of saidsurface adjacent said edge to a necking-in action whereby a portion ofthe metal flows from said edge and a portion from the cylindricalperiphery of said sheet metal member, and utilizing said curled overedge as a reinforcing means during the flowing of the metal and formingof said necked-in portion.

7. The method of forming a relatively deep bead adjacent the edge of amoving wall of sheet metal, in a single operation, which comprisesshaping an edge of said moving wall to reinforce and stiffen the same,subjecting a localized portion of said moving wall at a point spacedfrom but adjacent said edge to forming tools of predetermined shapewhereby to draw metal from said wall and distort the same laterally intoa shape corresponding to the shape of said forming tools, and utilizingthe shaped edge of the moving wall as a reinforcement means duringsubstantially the entire forming action whereby metal may flow from saidedge during the forming action.

8. The method of forming a relatively deep draw adjacent the edge of amoving wall of sheet metal, which comprises shaping an edge of saidmoving wall to reinforce and stiflen the same, subjecting a localizedportion of sa d moving wall at a point spaced from but adjacent saidedge to forming tools of predetermined shape, portions of said formingtools cooperating to confine said shaped edge beyond a plane defined bysaid cooperating portions of the forming tools, causing relativemovement between said forming tools to distort said moving walllaterally, a portion of the metal flowing from said shaped edge duringthe drawing action, and utilizing the shaped edge of the moving wall asa reinforcing means during the entire forming action.

9. The method of necking-in the peripheral wall of a substantiallycylindrical unit such as a washing machine tub and the like, whichcomprises causing relative movement between the peripheral portion to beformed and forming units having complemental eifective forming surfaces,maintaining the extreme peripheral edge portion of the unit beyond aplane defined by one edge of the effective forming surfaces of theforming units, and subjecting the rim portion adjacent said extreme edgeportion to a forming action whereby a portion of the metal in said rimportion is drawn away from said edge portion while said edge portion ismaintained beyond said plane. a

10. The method of necking-in the peripheral wall of a substantiallycylindrical unit such as a washing machine tub and the like, whichcomprises causing relative movement between the peripheral portion to beformed and forming units having complemental effective forming surfaces,maintaining the extreme peripheral edge portion of the unit beyond aplane defined by one edge of the effective forming surfaces of theforming units, and subjecting the rim portion adjacent said extreme edgeportion to a plurality of successive forming actions whereby a portion,

of the metal in said rim portion is drawn away from said edge portionwhile said edge portion is beyond said plane.

11. The method of forming rims of washing machine tubs and similararticles which com- 12. The method of forming rims of washing machinetubs and similar articles which comprises curling over the edge of theytub to forma reinforcing rim, setting up relative movement between thetub and forming units of predetermined shape, subjecting the rim portionof the tub to the forming units, whereby to give said rim portion theshape of the forming units, and maintaining said curled edge beyond aplane defined by cooperating portions of said forming units during saidforming action whereby said reinforced rim causes at least a portion ofthe metal in said formed part of the rim to be drawn from the side wallsof the tub between the said curled portion and the bottom of the tub.

13. A mechanism of the character described, comprising rotating formingrolls, one being reciprocably movable relative to the other, one of saidforming rolls having a shouldered portion adapted during at least partof said reciprocal movement to receive a preformed edge formed as a partof the article being subjected to forming action by the rolls, saidother roll having a portion cooperating with said shouldered portion tomaintain said edge beyond a plane defined by said cooperating portionsduring the movement of one of the forming rolls towards the other, saidforming rolls being so shaped and spaced relative, to each other that afree retainer ring may be positioned between the shafts of therespective forming rolls and clamped around the article being formedwhereby said ring will move with said article.

14. The method of cold forming a relatively deep draw adjacent the edgeof a moving wall of sheet metal, which comprises preshap'ing an edge ofsaid moving wall to reinforce and stiffen the same, subjecting alocalized portion of said moving wall at a point spaced from butadjacent said preshaped edge to forming tools of predetermined shapewhereby to form and bend said moving wall into a shape corresponding tothe shape of said forming tools, said preshaped edge acting as areinforcing means during the greater part of the forming and bendingstep to maintain the shape of the edge of the moving wall and controlthe flow of metal into the drawn portion.

15. .A mechanism forforming rims of washing machine tubs and similararticles comprising rotating forming rolls, one being reciprocallymovable relative to the other, said forming rolls having a diametersubstantially smaller than said tubs and having cooperating portionsadapted to 1 faces whereby said edge functions as a hold-down during thegreater part of the movement of one forming roll towards the other whilethe portions of the 'tub adjacent said reinforcing edge are beingformed.

16. A mechanism for forming a relatively deep draw adjacent the edge-ofa moving wall of sheet metal, comprising rollers radially movablerelative to each other, one roller located on one side of said wall andthe second on the other side, said rollers having opposed radialsurfaces spaced axially to positively confine and exert pressure on alocalized portion of the edge of said wall whereby said edge functionsas a hold-down, during the forming of said deep draw when both rollthedrawing action.

ers are rotating in opposite directions andmoving radially toward eachother, said hold-down action causing a portion of the metalto flow inroller dies, holding the shaped edge in afixed plane, and cold workingthe metal adjacent to said shaped edge by rotating the dies and movingthe axes thereof relatively toward one another; which workingsimultaneously rolls the metal, increases the cross sectional lengththereof, reduces the diameter of the article, and flows metal from saidarticle to the reduced portion to form the desired reduced neck shape.

18. The method of forming a reduced neck at an end of a cylindricalclosed bottom sheet metal article which includes the steps of shaping anedge at the open end thereof, supporting the article between rollerdies, engaging and holding the shaped edge in a fixed plane, pressingagainst the closed bottom of the article, and working the metalintermediate the extremities of the article and adjacent to said shapededge by rotating the dies and moving the axes thereof relatively towardone another; which working simultaneous ly rolls the metal, increasesthe cross sectional length thereof, reduces the diameter of the articleto form a curved wall between the reduced neck and the side walls of thearticle, and draws a, portion of the metal from the article to thereduced neck.

19. A mechanism of the character described, comprising rotating formingrolls, one being reciprocably movable relative to the other, saidforming rolls having cooperating portions adapted to confine areinforcing edge portion of the article being subjected to formingaction by the rolls whereby said edge portion functions as a hold-downduring the greater part of the movement of one forming roll towards theother, one of said forming rolls having a shoulder relative to whichsaid edge portion is spaced when the forming rolls move relative to eachother but which shoulder at least a part of which the edge portion isadapted to contact during the latter part of the forming action.

20. The method of necking-in the peripheral wall of a substantiallycylindrical unit such as a washing machine tub and the like, whichcomprises causin relative movement between the peripheral portion to beformed and forming units having complemental effective forming surfaces,maintaining the extreme peripheral edge portion of the unit beyond aplane defined by one edge of the efiective forming surfaces of theforming units, subjecting the rim portion adjacent said extreme edgeportion to a forming action whereby a portion of the metal in said rimportion is drawn away from said edge portion while said edge portion ismaintained beyond said plane,

.' andshearing off the edge portion and a part of the rim portion at thecompletion of the forming action.

21. A mechanism for forming rims of washing machine tubs and similararticles comprising rotating forming rolls, one being reciprocablymovable relative to the other, said forming rolls having a diametersubstantially smaller than a tub and having cooperating forming portionsadapted to confine a localized edge portion of .a tub beyond theeffective surfaces of said forming portions whereby said localizedportion functions as a reinforcing hold-down during the movement of oneforming roll towards the other while the portions of the tub adjacentsaid localized edge are being formed and shearing means positionedadjacent the cooperating forming portions of said rolls for cutting offan edge portion of the tub at the completion of the forming step.

DANIEL BOHM.

